Liquid crystal displays (LCDs) are a well known form of flat panel display. As is well known to those having skill in the art, a liquid crystal display includes a thin film transistor (TFT) substrate that includes a plurality of spaced apart gate lines having first and second ends and a plurality of spaced apart data lines having first and second ends. The plurality of spaced apart data lines intersect the plurality of spaced apart gate lines, generally orthogonally. Liquid crystal displays also generally include a color filter substrate opposite the thin film transistor substrate, and a liquid crystal material between the thin film transistor substrate and the color filter substrate. Each intersecting area of a gate line and a data line includes a thin film transistor and a pixel electrode, to form switching devices. Other flat panel displays may also include a plurality of spaced apart first conductive lines and a plurality of spaced apart second conductive lines on a display substrate, with a plurality of spaced apart first conductive lines intersecting a plurality of spaced apart second conductive lines.
As the size of liquid crystal displays continues to increase and the resolution of liquid crystal displays continue to increase, larger numbers of data lines and gate lines may be formed on the thin film transistor substrate. In fabricating such large numbers of lines, it is desirable for these lines to have low resistance and high durability. Moreover, as the number of lines increase, the likelihood that one of the lines is open circuited also generally increases. Accordingly, it is desirable to provide repairing structures and methods in order to allow a flat panel display to be utilized notwithstanding a short circuit therein.
For example, U.S. Pat. No. 4,688,896 to Castleberry describes a liquid crystal display that includes auxiliary address lines that are used to provide electrical communication with portions of main address lines that, due to the presence of electrical open circuits, would otherwise be electrically isolated. Each auxiliary address line crosses over multiple main address lines, and can be electrically shorted to any such main address line to provide electrical communication therewith. Similarly, for a gas discharge display panel device, U.S. Pat. No. 4,304,450 to Bilsback et al. discloses a repair cable having a plurality of conductors that runs from a termination area at one end of a conductor array to the termination area at the other end of the array. To repair an open circuit, opposite ends of a respective repair cable conductor are connected to the open conductor repair pads.
Unfortunately, as larger liquid crystal display panels having thinner gate lines and data lines are developed, the use of a repair line may unacceptably increase the resistance-capacitance (RC) time delay for the repaired data line or gate line.
Referring now to FIG. 1, a conventional liquid crystal display, including repair lines, and a method for repairing broken data lines will be described. FIG. 1 is a top view of a thin film substrate 10 including repair lines to repair open circuits in the thin film substrate. As shown in FIG. 1, a plurality of gate lines 11 extend horizontally, and a plurality of data lines 13 extend vertically on the thin film substrate 10. Input pads 15 are included at an end of each of the gate lines 11 and data lines 13. A pixel 17 is formed in a pixel region 19 at the intersection of a gate line 11 and a data line 13. A plurality of repair lines 20 is also included, that cross the data lines 13 outside the pixel region 19.
Referring now to FIG. 2, the method of repairing broken or open circuited data lines using the repair lines 20 is shown. As shown in FIG. 2, intersecting points 31 and 35 where broken data lines 13 meet the repair lines 20, are connected to a repair line 20 using a laser beam or other conventional technique. Thereafter, the repair line 20 is cut at positions 33 and 37. Accordingly, when pixel signals are applied to the broken data lines, the pixel signals go around through the repair line 20 and reach broken points A and B of the broken data lines 13.
As shown in FIG. 2, a single data line generally is repaired using a single repair line. Moreover, depending on the location of the broken data line, a large delay may be introduced due to the resistance and capacitance of the repair line between the opposite ends of the broken data line. This increased delay may be excessive for large, high resolution liquid crystal displays.